The Ann Arbor Geographic Information System is a series of GIS layers maintained by the City of Ann Arbor with detailed maps of city infrastructure.
http://www2.a2gov.org/gisonline/Inventory/inventory.asp
Some of these layers have been published for public use on http://a2gov.org/data .
City of Ann Arbor: Mayor | Council | City Administrator | Clerk | Elections | Police | Fire | Water | Sewer | Parks | Building | Planning | Zoning | Permits | Streets | Sidewalks | DDA | Historic Districts | FOIA |